Command-to-line-of-sight (CLOS) systems such as a laser beamrider have the disadvantages of requiring the gunner to be exposed during the missile flight and of depending on the gunner's ability to maintain LOS between the tracker optics cross-hairs and the target within a foot or so with a handheld launcher under stressful battlefield conditions.
Fire-and-Forget systems such as inertially guided or two-color infrared (IR) systems have the advantage that the gunner can take cover as soon as the missile is locked on and launched. They are sensitive, however, to conditions which cause temporary obscuration (artificial or natural) of the target during flight. In addition, limited target image resolution at launch (for maximum range targets) and/or a change in the approach angle during flight may cause the impact point to be less than optimum. If a correlation tracker is used, aimpoint drift during flight is also a problem.